The invention relates to the use of acacia gum (or gum arabic), alone or in combination with a sulfur-containing amino acid, for improving the growth and survival of bifidobacteria entering into the manufacture of fermented food products.
Bifidobacteria are one of the most commonly used probiotic microorganisms nowadays in the manufacture of various food products, and in particular of fermented dairy products.
Probiotics are defined as “live microorganisms which, when consumed in adequate amounts, confer a health benefit on the host” (report of the mixed consultation of FAO/WHO experts on the evaluation of the health and nutritional properties of probiotics in foods, 2001). This definition implies that to exert its beneficial effect, the relevant microorganism should be present in a sufficient amount in the ready-to-consume product. It is generally considered that this amount should be at least equal to 107 cfu/ml. Maintaining the viability of probiotic bacteria during manufacture, packaging and storage of food products containing them therefore constitutes an essential component of the quality of these products.
The species of bifidobacteria most widely used in the food sector are Bifidobacterium adolescentis, B. bifidum, B. breve, B. longum, B. animalis and B. infantis. 
In the context of the manufacture of fermented food products, the bifidobacteria may be used alone; however, they are most often, for organoleptic and/or technological reasons, combined with other lactic acid bacteria. They are in particular frequently combined with yogurt ferments (L. Bulgaricus and S. thermophilus). They may be added to already fermented products or, more commonly, mixed with other lactic acid bacteria, during inoculation of the substrate to be fermented.
Under the conditions for carrying out the manufacture of food products, the growth of bifidobacteria is frequently slow; in addition, at the end of the fermentation, it is often difficult to maintain a sufficient bifidobacteria population during the whole period of storage of the product up to its consumption. These problems may be increased if the bifidobacteria are combined with other lactic acid bacteria. Because of the low competitiveness of bifidobacteria in mixed culture, they often grow more slowly in the presence of other lactic ferments than when they are cultured alone; otherwise, their survival during storage of the fermented product is generally poorer, in particular, especially since some other lactic acid bacteria continue to produce, amongst others, lactic acid. This phenomenon, known as post-acidification, affects the viability of the bifidobacteria present in the same product.
In this context, it seems desirable to stimulate the growth and increase the viability of bifidobacteria, and preferably, to do this while inducing little or no effect (positive or negative) on the growth and viability of the lactic acid bacteria with which these bifidobacteria are combined.
The inventors have discovered that the use of gum arabic during the manufacture of fermented products made it possible to obtain these results.
Gum arabic is produced by exudation of wounds of the trunks or branches of certain species of acacia. It is a highly branched, high-molecular-weight, water-soluble polysaccharide. The gum arabic used as food additive (E414) is obtained exclusively from Acacia seyal or Acacia senegal. 
It has been proposed to use gum arabic to encapsulate probiotic bacteria (various bifidobacteria and Lactobacillus paracasei) in order to preserve them from heat and dehydration during drying, and to improve their viability, and their resistance to the gastric fluids and to bile (Lian et al. 2002; Lian et al. 2003; Hsiao et al. 2004; Desmond et al. 2002).
It has also been reported that the ingestion of gum arabic in humans, in an amount of 10 grams per day, made it possible to increase the Bifidobacterium and Bacteroides population in stools; more recently, a similar study has described an increase in the total population of lactic acid bacteria, and mainly of Bifidobacterium and Lactobacillus, after ingestion of 10 to 15 grams of gum arabic per day (Wyatt et al. 1986; Cherbut et al. 2003).